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Ok I will premise this with 2 things. Firstly I know that food trucks do not fall under the NEC and secondly, I know little about gensets.

We were asked to wire a food truck for a customer. We got the truck wired and then he shows us the genny. I have never seen one with this setup. It is a cummins genny made specifically for food trucks. The nameplate is 58 amps 120V. The leads coming from the genny are connected to a 2p 30 amp breaker which I assume are in phase. The leads are 2- #12 white, 1- #12 Black, 1- #12 Black with yellow tracer and a #12 green

Here is the schematic--- My question is whether or not this is a setup for parallel wiring. In other words do I parallel the neutrals and hots or what?
 
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Ok I will premise this with 2 things. Firstly I know that food trucks do not fall under the NEC and secondly, I know little about gensets.

We were asked to wire a food truck for a customer. We got the truck wired and then he shows us the genny. I have never seen one with this setup. It is a cummins genny made specifically for food trucks. The nameplate is 58 amps 120V. The leads coming from the genny are connected to a 2p 30 amp breaker which I assume are in phase. The leads are 2- #12 white, 1- #12 Black, 1- #12 Black with yellow tracer and a #12 green

Here is the schematic--- My question is whether or not this is a setup for parallel wiring. In other words do I parallel the neutrals and hots or what?

It looks like it to me,also I would wire it just like a commercial kitchen,210.8(B)...
 

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Looks to me like they've taken a dual-voltage single-phase generator and reconfigured it for 120V loads. I.e.: If they wanted to, they could also wire that for 240V applications without using a different stator.

So in your setup those windings would be in phase, and the current would be additive: That's why they doubled up the neutral conductors.

I can't think of anything off hand that would prevent them from being paralleled as long as you observed the same conductor sizes, and I would parallel the neutrals onto a common bus. But for simplicity because the hots are already on separate generator breakers, I would land each on it's own bus leg in a small single-phase panel. In the event that one leg does down, this also allows you to continue running, whereas a parallel installation would fail completely.
 

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Discussion Starter · #4 ·
Looks to me like they've taken a dual-voltage single-phase generator and reconfigured it for 120V loads. I.e.: If they wanted to, they could also wire that for 240V applications without using a different stator.

So in your setup those windings would be in phase, and the current would be additive: That's why they doubled up the neutral conductors.

I can't think of anything off hand that would prevent them from being paralleled as long as you observed the same conductor sizes, and I would parallel the neutrals onto a common bus. But for simplicity because the hots are already on separate generator breakers, I would land each on it's own bus leg in a small single-phase panel. In the event that one leg does down, this also allows you to continue running, whereas a parallel installation would fail completely.

That is exactly what I was thinking except that I was going to parallel the hots also. If one overloads so will the other as they are connected to a common dp breaker
 

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Discussion Starter · #5 ·
I am definitely not going to mes with the inside of the genny as the tails are already out. Surprising to me is that they parallel #12 to get 58 amps when #12 is 20 amps --- supposedly

On second thought I think you John is correct about splitting the hots to each phase.
 

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Discussion Starter · #6 ·
It also states
1. These are not reconnectable generators
2. Because generator windings T1-T2 and T3-T4 are in phase the neutral conductor in the connected equipment such as between the transfer switch and main distribution panel must be sized to carry the sum of the load.
I guess they decided to parallel 2- #12 to get a possible 58 amps????? but want the field to run full size-- well in this case there is no transfer switch just generator power.
 

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Discussion Starter · #8 ·
Thanks John. My guys are finishing it up so it was good to get the feed back. We don't usually work weekends so I gave them this job to do and get paid from the owner. They will appreciate the extra bucks.
 
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The neutrals would be paralleld, use a number 6. Keep the phases separate as a #12.


As big john said, the phase angle is the same. Best way to think of this is 2 12 volt car batteries. Normally they would be connected in series - + -+, the outer most terminals would give 24 volts while the inner 2 terminals jumped would be the neutral point. The neutral would never see double the ampacity because the neutral current is subtractive. However in this case we are dealing with a - + + - setup. Im essence we are no longer dealing with series windings but paralleled. The neutral is now additive an only 12 volts would be available between neutral and hot while 0 between the 2 hots. In this case its just windings in AC with 120 volts.


Top most is the gen bottom left is typical 120/240:
 

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Discussion Starter · #10 ·
The neutrals would be paralleld, use a number 6. Keep the phases separate as a #12.
Can't do. They have factory #12's paired coming from the genset. This unit has the leads already coming out of the genny

The battery analogy is a good one. I read that analogy many years ago from a member at mike holt forum. Thanks
 

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Discussion Starter · #13 ·
The interesting thing is the manual says that the unit is equipped with #10 125C irated insulation for the power. NOT-- its is #12
 

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I guess they run floating then. I only ask because normally on home gens the neutral is jumped to the egc in the housing like in a service to give the neutral a ground reference.


But I guess since its only 1 or 2 machines connected to the gen the system ungrounded might actually be safer.


Any GFIs on the plugs?
 

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Discussion Starter · #15 ·
We install a small 12 circuit panel and installed all gfci protected outlets inside and outside the truck.
 

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I guess they run floating then. I only ask because normally on home gens the neutral is jumped to the egc in the housing like in a service to give the neutral a ground reference....
Seems like it could still well be. I'd check to be sure there was already a bond between the neutral and supplied EGC and if so, wire accordingly.
 

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It would help a lot if they put dots on the transformer windings shown in the schematic. With dots you always know how to correctly connects windings.

You probably want to skip the ground rod on this installation.:)

EJPHI
 
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